How to scale vertices uniformly in one direction?
Pivot is the origin, not the goal.

The pivot point is considered the origin of the transformation space. Scaling the objects with a factor smaller than 1 will make them collapse toward the origin, while what you would like to achieve is verteices spreaded from the origin toward another point. The scaling factor should be greater than 1 in this case (e.g. the double, the triple...).

I suggest to change the position of the 3D cursor to the symmetry axis instead of the goal point. This way you'll be able to scale your vertices uniformly, even if they are not evenly spaced.